How could I forget? Mega Man.

The Blue Bomber IS his own genre and style of game at this point, but when the original hit the shelves, it was something new and fun and amazing. My first Mega Man is another gaming milestone I'll never forget.

I think i will add in agreement with a lot of others games like portal and smash bros. Also, majoras mask, simply because of how it handled the story and the world.

Its friendly and nice enough that kids can enjoy it, whilst those with a more developed sense of black humor can laugh themselves ragged on just how bloody dark the game is, twilight princess dark my arse, majoras mask did things that game wouldn't even contemplate. As well, the game wasn't afraid just to add a what the hell moment into the mix.

Last but not least killer 7. If I ever play a cooler game i will tell you. Somehow it took the idea of a very simple, very flawed system of interacting with the game world (can only walk in a predetermined line whereas everything else in the game is under no such condition) and some poor, if not illogical puzzles at times and made me love it and want to play more. Most games would have been crushed under killer 7s game play flaws. Killer 7 makes it so you don't care, and somehow just use it enhance the games weirdness.

Definitly Earthbound. One of the best RPG games hands down.

Chrono Trigger for sure, did the RPG genre a great service.

Phoenix Wright & Trama Center: Worked really well to open up games into professional feilds.

Viva Pinata, Dead Rising & LocoRoco

I don't understand the people saying Half Life 2... its gameplay was virtually identical to Half Life 1.

As for me, the original Sonic the Hedgehog drew me into gaming with its unique super high speed style of platforming.

The_root_of_all_evil:
Paradroid (you're a possesion droid capturing Daleks)
Wizball (You're a Wizard trying to regain colour for his land from Aliens, whilst avoiding the Police)
Wicked (You're Good, trying to fight off Evil using the Tarot)
Weird Dreams (You're a guy on an operating table, trying to wake up before the dreams kill you)
Anything by Jeff Minter or Tim Schafer.
Sam And Max. (Sic 'em, little buddy)
Another World (Precursor to Half-Life?)
Quake (Real Time Networked Games?????)

Wizball! Now that takes me back. I still have the theme sound when the police arrive burnt into my brain.

Morrowind was another that I was completely absorbed into, not so much with Oblivion (although the graphics were insanely beautiful.)

I'll have to check out Weird Dreams, sounds very interesting. Day of the Tentacle and Sam & Max were also favourites of mine along with Simon the Sorcerer.

Syndicate was another game that blew me away at the time.

Okami
GTA 3
Rome total war

Maniac Mansion
Fight Night (the boxing game)
Skate
GTA 3
Rockstar's Ping Pong
Ultima VIII
720

Elite Beat Agents/Ouendan, and Guitar Hero.
As far as I know, there weren't very many Rhythm games with original gameplay before these games. They are great, and they really broke the mold, proving that it doesn't need to be DDR or something like that to be good.

Katamari Damacy. I challenge you to find anything even remotely like it before or since (discounting the sequels, obviously.)

Garry's Mod is the most unique game I've ever played. To get such an amazingly diverse and virtually infinite set of gameplay elements for 10 bucks is one of the greatest values in the video game industry.

its gameplay was virtually identical to Half Life 1.

Well, first, Half Life 2 is a lot more fun to play. Then, the physics engine, the fact that you could handle every single one of the objects present in the game, and the gravity gun were really new. The shooting part is the same, but the interacty with the environnement was, I think, a first. The game also set new standarts of storytelling from a first person point of view. In previous FPS, you didn't have that kind of interactions with characters out of cutscenes, plus, the facial animation system helped a lot.
So yes, the gameplay wasn't that different, but the game set new standarts with a lot of little new features.

Artheval_Pe:

Warcraft III : for the introduction of RPG elements (Heroes, XP, items, etc...) in a RTS in a very successful way

Half Life 2 : for the interaction with the world, the physics, the design of the characters

STALKER : for the free non-linear FPS-RPG experience, the A-life system, the day/night cycles and the unique atmosphere of the game.

the thing is with this is..

Warcraft III would have been nothing without Warcraft or Warcraft 2, Half Life 2 didn't break anything, the original did. As for the rest...STALKER? Deus Ex anyone? Much better, less buggy and Bioshock was just a shallower remake of System Shock so its not entirely breaking new ground.

Total Annihilation, Doom, Quake, Sim City, DoTT, Manic Mansion, Monkey Island, Elite, Ultima series - these are some of what broke the mold

Super Mario Bros: The father of all platformers. Introduced tight gameplay.

The Legend of Zelda: Action-RPG's first and best. Ocarina of Time introduced locked targeting for 3-D games.

Castlevania II: Shifting from day to night, the whole world changes in between.

Doom: FPS' birth

Starcraft: Actually made RTS' fun and balanced.

Half Life: FPS to the next level.

Grim Fandango: Original and superb storyline. An amazing cast of characters, one-liners and voice acting. Extremly fun.

Eternal Darkness Sanity's Requiem: Multiple characters, tight storyline and the amazing sanity meter.

Call of Duty: Total immersion and tension in a game. First war game where you actually fear wars and hope they didn't exist.

Out of this World: Gameplay, such a differente storyline.

Pro Evolution Soccer 2008 (Wii): It's a glimpse of things to come. You have to be a soccer fan to fully appreciate what the control scheme does to soccer games.

Guitar Hero: Probably the most addictive rythm game, and it changed how you enjoy music.

Myst: Adventure games catalyst.

Silent Hill: Survival horror taken to a psychological level, especially Silent Hill 2.

carlosvader77:
Doom: FPS' birth

Guitar Hero: Probably the most addictive rythm game, and it changed how you enjoy music.

Myst: Adventure games catalyst.

Silent Hill: Survival horror taken to a psychological level, especially Silent Hill 2.

To agree and correct you on some instances (just to give credit where credit is due).

Doom was't the first. Wolfenstien was before Doom, so I would consider it the Mold breaker for the FPS. However, Doom introduced network play, so I would consider it the mold breaker and front runner for all the multiplay fun we currently enjoy with COD4 and GeOW.

Myst: Couldn't agree more

Guitar Hero: Also quite ground breaking.

Silent Hill was not the first: Resident Evil actually coined the phrase Survival Horror even though Alone in the Dark was realeased first. But I think there was one "Survival Horror" game even before that. A game called Clock tower where you are constantly being chased by a guy with a huge pair of cutting shears.

Not to dissagree with you: I think the type of games (FPS and Survival horror) are groundbreaking, just I think credit should be given to the first one to do it.

http://en.wikipedia.org/wiki/Survival_horror

Another World!
The things it managed to achieve with a development team of ONE and a music team of ONE were enormous.

shatnershaman:
Halo: Combat Evolved-Stuck it to all those that said dual analog console FPSs suck.

Well the next two reminded me why I hate them :P

Jonathan Hexley:
Elite Beat Agents/Ouendan, and Guitar Hero.
As far as I know, there weren't very many Rhythm games with original gameplay before these games. They are great, and they really broke the mold, proving that it doesn't need to be DDR or something like that to be good.

THANK YOU! OH GOD, THANK YOU! I was waiting for someone to drop the ball on these. I was worried that I would have to be the one to break the mold (no pun intended) here. I support everything in this post, Guitar Hero especially. Who would ever think to make a game where people could shred on cheapo plastic guitars in their own living room?

Let's not forget Dune, RTS forerunner.

Mad props to Thief - One of the first first-person sneakers. Also, the great mix of magic and pre-industrial steampunk was very unique. I also love the fact that there is no hammy good vs. evil B.S., just factions with extreme ideals.

The_root_of_all_evil:

Another World (Precursor to Half-Life?)

You sir, are made of win.
Another World was Epic as was Flashback, two games i only thought i had played. Until now.

As for mold breaking, Monkey Island.

KOTOR-Maybe deus ex did it before but this time theres, Lightsabers, A actually good star wars game.
MGS-I guess it created a decent sneaking experience
Fable-A great somewhat colorful WRPG.
C&C-Intense RTS
Portal-Puzzler but a great one
TF2-A remake of the first but tweaking to perfection.
Crysis-Because it makes real life look like crap

i'm going to say Halo 1

It brought a whole bunch of easy features together and i think it was something special in the world of FPS.

friedmetroid:
I don't understand the people saying Half Life 2... its gameplay was virtually identical to Half Life 1.

I don't remember having a gravity gun in the first Half-Life, or such amazing characters.

Madlarkin:

Another World was Epic as was Flashback, two games i only thought i had played. Until now.

Thank You! I thought I was alone with Flashback.

Also
Monkey Island
Guitar Hero
Half Life
Half Life 2
Sim City
Devil May Cry
Grand Theft Auto 3
Final Fantasy VII
Ok, the whole RPG had been done before many times over, but as far as I know no other game killed off a playable character.

How is Morrowind breaking the mold? Look up Daggerfall. Point out some games that actually did something really new and exciting and (in general)failed utterly because they didn't suit the zeitgeist.

Planescape: Torment
System Shock 2
Thief
Deus Ex
Portal
Maaaybe S.T.A.L.K.E.R.
Fahrenheit/Indigo Prophecy
Arcanum
Shadow of the Colossus
Penumbra series
EVE Online
Spore

Psychonauts. Seriously, that game is so good. Like Yahtzee said (FYI: Played it before I saw the review) it's something new. I can remember my cousin playing it and him laughing at the characters and me laughing at the dark humour of it all. I mean, the book depository with the government agents? It was an awesome game. Never played anything as awesome.

Saevus:
How is Morrowind breaking the mold? Look up Daggerfall. Point out some games that actually did something really new and exciting and (in general)failed utterly because they didn't suit the zeitgeist.

Planescape: Torment
System Shock 2
Thief
Deus Ex
Portal
Maaaybe S.T.A.L.K.E.R.
Fahrenheit/Indigo Prophecy
Arcanum
Shadow of the Colossus
Penumbra series
EVE Online
Spore

True about Daggerfall, but you are also doing it with System Shock 2. What about System Shock one? It was definitely different for it's time, but was over shadowed by Doom and Warcraft at the time. It had a wonderful, complex interface and inventory with a rich cyberpunk story. It tried lots of things and succeeded with most. System Shock 2 was a refinement.

Most everything Trokia did was mold breaking (Temple of Elemental Evil, Arcanum, Vampire the Masquerade). Only they smashed the mold so hard, they broke their games in the process.

Portal, obviously.

The original Myst broke the mold.

I believe Legend of Zelda: Majora's Mask definitely broke the mold for the Zelda series, and put a fun twist on action-RPGs in general.

Goldeneye: the real cause behind console FPS's.

Kingdom Hearts, obviously, broke several molds.

Definitely, S.T.A.L.K.E.R. I seriously think it is one of the best games ever.

The Original Half-Life is definitely one, if you were alive and into the PC gaming scene in '98.

Half-Life 2, basically for the same awesome reasons as its predecessor.

Even though I'm not much of a Nintendo person (especially since the Wii came out), but I love Ocarina of Time.

Unreal Tournament, because we were shown how awesome it is to explode people into tiny bits and laugh.

Grand Theft Auto III, because that was the dawn of the 3D Open World environment.

Obviously Conkers Bad Fur day, for mixing an anthropomorphic Platformer with, well, I don't know wehat, but it was great. Which made Live and Reloaded all the more a slap in the face from Microsoft. If you want one reason why I hate them, that would be it.

Also Pokemon Snap. Be honest, how many of you, before that game, would have thought a damn photography game would be any good.

Metal Gear, as it was the first full on Stealth game.

The Monkey Island series of adventure games.

Nothing comes close in terms of sheer wacky hilarity. Tim Schafer, Ron Gilbert, and Dave Grossman are all geniuses in their field.

It also has one of the most memorable theme songs of all time by Micheal Land.
It's pure awesomeness.

LucasArts, where did you go wrong?

the upcoming game Little Big Planet would really break the mold. It's a pretty diff platform and I can't wait for its release at October.

Little Big Planet PS3 | Xbox 360

bleuish:
the upcoming game Little Big Planet would really break the mold. It's a pretty diff platform and I can't wait for its release at October.

Little Big Planet PS3 | Xbox 360

Did you link the 360 thing in the attempt to fool someone into thinking it was also on the 360? Or does the site have some claim that LBP will be on the 360?

In no particular order... (or, some games that come to mind as i think..)

Portal,Abe's Oddessy,Lemmings,Wolf3D,Descent,Quake,Unreal Tournament,Crystal Caves,Doom,Captain Comic,Choplifter,Counterstrike

Showing my age here but..

Elite - on the spectrum.